At present, dynamic effects such as time-dependent dimming or color variation are being applied more and more in lighting applications. Fluorescent lamps may also be applied in such lighting applications. In order to provide dimming capabilities for such lamps, solutions have been proposed. Dimming of a fluorescent lamp can be accomplished by applying an electronic lamp driver enabled to drive the fluorescent lamp at a varying frequency, thereby providing a varying current to the lamp. Dimming is thus obtained by changing a switching frequency e.g. of a half-bridge circuit. The application of such an electronic lamp driver however is rather expensive due to the requirement of ICs to control the lamp driver. As fluorescent lamps having dimming capabilities are highly suited for domestic applications, the application of expensive components should be avoided. In addition, frequency-dimming methods such as PWM dimming, that are not synchronous with the e.g. 50 Hz (or the 100 Hz rectified) mains voltage, usually cause flickering when applied at low frequencies.
Instead of using an electronic lamp driver, it is known to start and power a fluorescent lamp (or light bulb) by using a self-oscillating inverter, e.g. a toroid inverter. Such inverters are known to be cheap compared to electronic lamp drivers. However, dimming by means of a frequency-dimming method cannot be applied in such a self-oscillating inverter. It is further known, e.g. from U.S. Pat. No. 6,380,692, to dim a lighting load by applying a controllable conductive device. Such a device (e.g. a TRIAC-based dimmer) provides a phase-cut AC voltage that can be applied for dynamically powering (e.g. enabling the intensity to be varied) certain lighting applications. A modified AC voltage, e.g. obtained as output voltage from a TRIAC-based dimmer, is not readily applicable for powering a fluorescent light bulb. In addition, the generation of the modified (e.g. phase-cut) AC voltage may require expensive high power electronic parts such as thyristors or TRIACs.